From owner-freebsd-stable@freebsd.org Sun Feb 7 22:18:26 2021 Return-Path: Delivered-To: freebsd-stable@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id BF9E753B4F2 for ; Sun, 7 Feb 2021 22:18:26 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from mailman.nyi.freebsd.org (unknown [127.0.1.3]) by mx1.freebsd.org (Postfix) with ESMTP id 4DYk7k4FLsz3lbV for ; Sun, 7 Feb 2021 22:18:26 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: by mailman.nyi.freebsd.org (Postfix) id 91B0553B819; Sun, 7 Feb 2021 22:18:26 +0000 (UTC) Delivered-To: stable@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 9177353B4F1 for ; Sun, 7 Feb 2021 22:18:26 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4DYk7k0SQMz3lW7; Sun, 7 Feb 2021 22:18:25 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.16.1/8.16.1) with ESMTPS id 117MICSE056450 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 8 Feb 2021 00:18:15 +0200 (EET) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua 117MICSE056450 Received: (from kostik@localhost) by tom.home (8.16.1/8.16.1/Submit) id 117MICgk056449; Mon, 8 Feb 2021 00:18:12 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Mon, 8 Feb 2021 00:18:12 +0200 From: Konstantin Belousov To: Alan Somers Cc: Mark Johnston , Matthew Macy , FreeBSD Stable ML Subject: Re: Page fault in _mca_init during startup Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on tom.home X-Rspamd-Queue-Id: 4DYk7k0SQMz3lW7 X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 07 Feb 2021 22:18:26 -0000 On Sun, Feb 07, 2021 at 02:33:11PM -0700, Alan Somers wrote: > On Fri, Feb 5, 2021 at 10:21 AM Konstantin Belousov > wrote: > > > On Fri, Feb 05, 2021 at 09:01:26AM -0700, Alan Somers wrote: > > > On Fri, Feb 5, 2021 at 7:41 AM Konstantin Belousov > > > wrote: > > > > > > > On Thu, Feb 04, 2021 at 07:53:09PM -0700, Alan Somers wrote: > > > > > On Thu, Feb 4, 2021 at 7:40 PM Konstantin Belousov < > > kostikbel@gmail.com> > > > > > wrote: > > > > > > > > > > > On Thu, Feb 04, 2021 at 07:01:30PM -0700, Alan Somers wrote: > > > > > > > On Thu, Feb 4, 2021 at 5:59 PM Konstantin Belousov < > > > > kostikbel@gmail.com> > > > > > > > wrote: > > > > > > > > Do you have INVARIANTS enabled? If not, I am curious if > > enabling > > > > them > > > > > > > > would convert that rare page fault into rare "CPU %d has more > > MC > > > > banks" > > > > > > > > assert. > > > > > > > > > > > > > > > > Also might be the output of the > > > > > > > > # for x in $(jot $(sysctl -n hw.ncpu) 0) ; do cpucontrol -m > > 0x179 > > > > > > > > /dev/cpuctl$x; done > > > > > > > > command will show the issue (0x179 is the MCG_CAP MSR). > > > > > > > > You need to load cpuctl(4) if it is not loaded yet. > > > > > > > > > > > > > > > > > > > > > > I don't have INVARIANTS enabled, and I can't enable it on the > > > > production > > > > > > > servers. However, I can turn those three KASSERTs into VERIFYs > > and > > > > see > > > > > > > what happens. Here is what your command shows on the server that > > > > > > panicked: > > > > > > > $ for x in $(jot $(sysctl -n hw.ncpu) 0) ; do sudo cpucontrol -m > > > > 0x179 > > > > > > > /dev/cpuctl$x; done | uniq -c > > > > > > > 16 MSR 0x179: 0x00000000 0x0f000c14 > > > > > > > 16 MSR 0x179: 0x00000000 0x0f000814 > > > > > > > > > > > > It probably explains it, but it would be more telling if you left > > the > > > > > > output as is, so that we can see which CPUs have MCG_CMCI_P (10) > > bit > > > > set. > > > > > > > > > > > > > > > > I didn't sort them, so the first 16 have bit 10 set and the second 16 > > > > > don't. > > > > > > > > > > > > > > > > > > > > > > I suspect that your machine has two sockets, and processor in one > > > > socket > > > > > > has CPUs reporting MCG_CMCI_P, while other processor does not. > > Your SMP > > > > > > is not quite symmetric, perhaps processors were from different > > bins? > > > > > > > > > > I found 2 other servers that exhibit the same problem: the first 16 cores > > > have bit 10 set and the second 16 don't. All 3 have dual Xeon Gold 6142 > > > CPUs and SuperMicro X11DPU motherboards with BIOS revision 5.12. I have > > > other examples of X11DPU motherboards that don't exhibit the problem, but > > > they all have both different CPUs and different BIOS revisions. So I > > can't > > > be sure whether the bug follows the CPU model or the BIOS version. > > I looked at the full spec update errata list for the first gen Skylake > > Xeons, but did not noticed anything relevant. EDS doc does not provide > > much useful info on the MSR 0x179 bit 10 either, except rewording SDM > > definition. > > > > In fact I am not sure but this bit might be writeable by software. Try > > to flip the bit with cpucontrol(8). Might be it is a BIOS bug after all. > > > > If you have Intel representative contact, or Supermicro contact, try to > > engage them. I do not have any further ideas, since spec update does not > > mention the problem. > > > > > > > > > > > > > > > > > > > > > > > > Could be. Is there some MSR that reports a more specific version > > number? > > > > There are CPUID %eax=1 values returned in %eax, but then it requires > > > > some interpretation. > > > > # cpucontrol -i 1 /dev/cpuctl$x > > > > for $x iterating over the cpus. > > > > > > > > > > Apart from the Local APIC ID field, that returns the same value for all > > > processors. > > > > > > Your second patch doesn't cause any obvious problems on my dev system. > > I hope that you would confirm that the issue is solved by it, after some > > time. > > > > Upgrading the BIOS fixed the problem, by clearing the MCG_CMCI_P bit on all > processors. I don't have strong opinions about whether we should commit > kib's patch too. Kib, what do you think? The patch causes some memory over-use. If this issue is not too widely experienced, I prefer to not commit the patch.